Function date_picker 

pub fn date_picker<'a, Message, Theme, F>(
    show_picker: bool,
    date: impl Into<Date>,
    underlay: impl Into<Element<'a, Message, Theme, Renderer>>,
    on_cancel: Message,
    on_submit: F,
) -> DatePicker<'a, Message, Theme>
where
    Message: 'a + Clone,
    Theme: 'a + Catalog + Catalog + Catalog + Catalog,
    F: 'static + Fn(Date) -> Message,

Shortcut helper to create a DatePicker Widget.